639400921191 has 24 divisors (see below), whose sum is σ = 939570974160. Its totient is φ = 418891620096.

The previous prime is 639400921189. The next prime is 639400921207. The reversal of 639400921191 is 191129004936.

639400921191 is a `hidden beast` number, since 6 + 39 + 400 + 9 + 21 + 191 = 666.

It is not a de Polignac number, because 639400921191 - 2¹ = 639400921189 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639400921111) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1269951 + ... + 1700463.

It is an arithmetic number, because the mean of its divisors is an integer number (39148790590).

Almost surely, 2^639400921191 is an apocalyptic number.

639400921191 is a deficient number, since it is larger than the sum of its proper divisors (300170052969).

639400921191 is a wasteful number, since it uses less digits than its factorization.

639400921191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 433375 (or 433372 counting only the distinct ones).

The product of its (nonzero) digits is 104976, while the sum is 45.

The spelling of 639400921191 in words is "six hundred thirty-nine billion, four hundred million, nine hundred twenty-one thousand, one hundred ninety-one".